With the development of wearable devices and the improvement of public awareness of environmental protection, the development of high-performance and green economic flexible electrochemical energy storage devices has become a research hotspot. Using biomass as a precursor to prepare energy storage materials with excellent performance can significantly reduce production costs and realize sustainable utilization of carbon resources, which has great development potential and practical application value. According to the composition and configuration of biomass-based flexible supercapacitors, this paper describes the electrode materials, flexible membranes and various assembly methods of flexible supercapacitors, introduces the electrode materials of flexible supercapacitors, analyzes the characteristics and advantages of wood based, cellulose gel based, paper based and biomass waste electrode materials, and expounds the research status of biomass-based flexible membranes. Including cellulose paper diaphragm and biological diaphragm; In addition, according to the overall performance and application field, three kinds of flexible supercapacitors are introduced: stacked type (sandwich type), interdigital type (micro-interdigital type), fiber type (linear type), and the performance differences of flexible supercapacitors with different assembly modes are compared. Finally, the challenges of biomass materials used in flexible supercapacitors are analyzed, and the future development direction of flexible devices is prospected.